Chronic obstructive pulmonary disease (COPD) is the commonest respiratory cause of mortality and morbidity in adults in the UK. Although the condition is initially a pulmonary one, data exist to support the concept that factors associated with COPD, including immobility, gives rise to secondary effects, including a quadriceps myopathy, which in turn cause anaerobic metabolism at low work rates. This, through bicarbonate buffering, leads to CO2 retention which, because of constraints imposed by pulmonary mechanics, cause acidosis and dyspnoea. Various therapeutic strategies to reverse this spiral may be employed including pulmonary rehabilitation, quadriceps strength training and surgical or bronchoscopic lung volume reduction.